Crux and Centaurus constellations. Starfield featuring the constellations of the Southern Cross (Crux Australis, right) and Centaurus (left). At centre right is the Coal Sack, an interstellar cloud (nebula) of dust which blocks the light of stars behind it. The crucifix-shaped Southern Cross is defined by four bright stars contained in the area from right to upper right. The two bright stars seen in Centaurus are Hadar (Alpha Centauri, blue) & Rigil Kentaurus (Beta Centauri, white). Alpha Centauri is the third brightest star in the sky; at only 4.3 light years distance, it is one of the nearest stars to Earth.